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Knife Gate Valve: Types, Functions, and Applications
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Table of Contents

Knife gate valves, also known as slurry gate valves or knife-type slurry valves, are essential components in industrial fluid control systems. Their unique design and excellent performance make them indispensable in handling complex working conditions across various industries. 

Table of Contents [Hide]
1 Types of Knife Gate Valves
2 Working Principle of Knife Gate Valves
3 Applications of Knife Gate Valves
4 Structure of Knife Gate Valves
5 Looking for China’s Best Knife Gate Valve Manufacturer? Get Your Quote from FLUIDO

Types of Knife Gate Valves

Classification by Sealing Type​​​​​​
Hard-seal Knife Gate Valve

These valves use metal sealing surfaces such as stainless steel or hard alloys. They offer high hardness and wear resistance and are suitable for high-temperature, high-pressure, and corrosive media environments.

Soft-seal Knife Gate Valve
Soft seals use elastic materials like rubber or PTFE. They provide excellent elasticity and sealing performance to prevent leakage effectively and are ideal for applications with high sealing requirements.

Classification by Structural Form​​​​​​
Parallel Knife Gate Valve

The gate plate moves vertically between parallel sealing surfaces. This structure is simple and easy to manufacture but has relatively lower sealing performance. It is used in low-pressure large-diameter pipelines.

Wedge Knife Gate Valve
The wedge-shaped gate enhances sealing by tightening against the seat. These valves provide superior sealing performance suitable for medium to high-pressure systems.

Working Principle of Knife Gate Valves

Closed State
In the closed position, the gate plate lies within the valve body tightly pressed against the seat using its wedge-shaped bottom edge to block fluid flow completely. The stem moves downward through the actuator mechanism increasing contact pressure on the seat surface to enhance seal integrity.

Open State
To open the valve, the actuator raises the stem which lifts the gate away from the seat gradually opening up fluid passageways without significantly impeding flow due to its streamlined knife-like design.

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Applications of Knife Gate Valves

Knife gate valves serve critical roles across multiple industries; in pulp and paper production, they cut through fibrous pulp and manage wastewater, while in petrochemical plants, they withstand corrosive, pressurized fluids. The mining industry relies on their wear resistance and self-cleaning action for abrasive slurries, and municipal drainage systems use them for rapid flow control of stormwater and sewage to mitigate floods. Furthermore, they meet the hygienic demands of food and beverage processing with easy-clean designs and ensure continuous operation in power plants by handling extremely abrasive fly ash in ash handling systems.

Upkeep is easier on OS&Y since threads are out and simple to grease. On NRS, threads touch the fluid and wear faster in harsh conditions.

OS&Y works best for visible, above-ground spots that need strong dependability. NRS fits buried or cramped areas well.

Structure of Knife Gate Valves

Valve Body

Made from cast steel, iron, or stainless steel. It’s strong against inside pressure. It holds all parts safely in exact-made spaces. Flanged ends connect to pipes easily.

Gate Plate

Shaped like a blade with slanted edges. It cuts through thick liquids easily. Materials can be carbon steel for normal use or stainless/alloy steels for harsh or rough settings.

Valve Stem

Connects the actuator to the gate. It moves the gate up and down. Usually made of stainless steel for strength and rust protection, even in tough pipe liquids.

Sealing System

Has seat rings (rubber, PTFE, or metal) and packing glands with graphite, asbestos, or PTFE. These stop leaks at the stem and keep the valve strong in hot or cold changes.

Actuation Devices

Options include handwheels (simple), electric motors (automatic), pneumatic cylinders (quick), or hydraulic pistons (strong). You pick based on how often it’s used, safety, or load needs.

Looking for China’s Best Knife Gate Valve Manufacturer? Get Your Quote from FLUIDO

As a leading manufacturer specializing in steel valves since 1994, FLUIDO provides custom-made knife gate valve solutions tailored precisely to your technical requirements—from material selection through actuation design—backed by ISO9001-certified quality assurance systems and CE-approved product lines exported globally across 35+ countries/regions worldwide. Contact us today at info@fluidovalve.com for your free quote!